Iproniazid (a derivative of isoniazid) was originally introduced because of its antituberculous properties, but for some time it has been known to have several other effects, some of which may be due to the fact that it inhibits mono-amine oxidase, the enzyme responsible for the inactivation of serotonin (5 hydroxy-tryptamine) and adrenalin. Recently, Cesarman (1957) Unfortunately, neither series was controlled, and before accepting these results it is important that they be confirmed by more critical study. Accordingly, a double blind trial was devised, the results of which are the subject of this paper.Selection of Patients. Over 170 patients with angina of effort attending the Department of Cardiology were interviewed, from which a series of 52 (45 men and 7 women) were selected. All were suffering from moderate or severe angina of effort, which had not undergone any change in severity within the previous six months. Patients receiving reserpine and those suspected of being unreliable witnesses were excluded.Alethod. At the initial interview, the severity of the symptoms was assessed using normal daily activities and the daily consumption of trinitrin as indices. Each patient was given a card to record his trinitrin requirements over the following three weeks, and was asked to note any side effects and the time at which improvement, if any, occurred. In the event of more than trivial side effects, patients were instructed to stop taking the tablets and report immediately.The patient's usual treatmdnt (peritrate, diuretics, digitalis, etc.), was continued as usual, the only alteration being the addition of the trial tablets that consisted of 50 mg. of iproniazid with a similar tablet of lactose as a control. The dose prescribed was one tablet, three times a day, i.e. 150 mg. of iproniazid. The tablets were distributed through the hospital pharmacy, neither the patients nor investigators knowing which preparation was being dispensed first. All patients were interviewed after three weeks when the tablets were changed over and again after a further three weeks when any improvement was assessed with particular attention to the relative efficacy of the two courses of tablets.
RESULTSOf the 52 patients who were started on the trial, 11 failed to complete it. This was due to aggravation of angina in two (both on the control tablets at the time) and the onset of myocardial infarction in one: this patient was taking iproniazid but we have no reason to suppose that it was responsible. Seven patients complained of various side effects but only three of these were taking iproniazid at the time, the others receiving control tablets: the remaining patient failed to reattend and the reason could not be ascertained. The trial was completed by 41 patients and all of them could be placed in one of four groups as shown in Table I. 323
